Change into passive voice:
Thieves broke into my house.

​- Since the given active sentence is in the past indefinite tense.
- The passive form will also be in the past indefinite tense.
- We use the third form of the verb in a passive sentence when we change an active sentence into a passive sentence.
- The active sentence is in the past indefinite tense, so in passive form was is used as a helping verb.
- The correct passive form is: My house was broken into by thieves.